AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING

Figure 2-18.- Testing an armature for a short circuit with a milliammeter.
Figure 2-19.- Testing an armature for grounds.
In testing individual armature coils for open circuits, use the test probes, as shown in
figure 2-20. Place them on the riser part of adjacent commutator bars, not on the brush
surfaces. If the test lamp does not light, there is a break some where in the coil. Repeat
this test on every pair of adjacent bars. Do this by walking the probes from bar to bar.
Should you find an open coil, the fault may be at the commutator connectors where it
is possible to make repairs with a little solder. If a coil is open-circuited internally, the
armature should be discarded.
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